CDL Air Brakes TestInspecting Air Brake SystemsHard
A technician is inspecting the air compressor on a commercial vehicle. They notice that the compressor's discharge line, connecting to the wet tank, is excessively hot to the touch. What does this condition most likely indicate?
- AThe compressor's unloader mechanism is stuck, causing continuous compression.
- BThere is excessive moisture in the air system, causing the compressor to overwork.
- CThe air compressor is working efficiently and building pressure quickly.
- DThe air dryer is malfunctioning and not purging correctly.
Show answer & explanationAnswer & explanation
Correct answer: A. The compressor's unloader mechanism is stuck, causing continuous compression.
An excessively hot discharge line from the air compressor often indicates that the compressor is continuously compressing air, even when the system is at full pressure. This usually points to a fault in the unloader mechanism, which is designed to stop the compressor from building pressure once the system reaches its maximum.
Why the other options are wrong
- B. Excessive moisture can lead to corrosion and other problems, but it wouldn't directly cause the discharge line to be excessively hot due to continuous compression.
- C. Efficient operation would not typically lead to excessive heat in the discharge line; excessive heat suggests overwork or continuous operation.
- D. While an air dryer malfunction can lead to other issues, it's not the primary cause of an excessively hot discharge line due to continuous compression.
Air Compressor Unloader Mechanism
The unloader mechanism in an air compressor stops the compressor from building pressure once the air system reaches its maximum, allowing the compressor to 'rest' or pump air without resistance.
- Regulates air pressure build-up.
- Prevents compressor from over-pressurizing the system.
- Failure can lead to continuous compression and overheating.
Memory trick: Compressor too hot? Unloader stuck, no rest for the hard worker.